Endurance voyages - Battery vs Diesel

[Corsair]

OK here we are again...

Without making tests, it's easy to make a fast calculation.

Let's say a VIIb has an autonomy of 8000 miles at 8 knts (it's close and makes it easier).
We run it on the surface at 8 knts, this gives us 1000 hours (which is the unit used on boats for fuel consumption)
Assuming the weather stays nice and beautiful (for making things easier) our sub A will run 8000 miles @ 8 knots in 41.66 days (1000 hrs / 24)

The same sub B runs in the same nice weather conditions, but is submerged 12 hours @ 3 knts, reloads batteries 3 hrs @ 5 knts and runs surfaced 9 hrs @ 8 Knts every day. This gives us 36 + 15 + 72 = 123 miles a day, which is average 5.125 Knts.

Since our sub B uses its diesels only 12 hrs a day, the 1000 hrs of autonomy give us now 83.33 days, for a total distance of 123 * 83.33 = 10 250 miles

So although it will take twice the time, sub B will travel 2.250 miles i.e. roughly 28% further than sub A in the same weather conditions.

Merry Xmas to all of you..

[fredbass]

Ducimus: I think you'd better drop this one. It seems somebody is confused between the game and reality. (I won't name names) He might have some sort of autism. :hmm:

[Letum]

Originally Posted by fredbass

Ducimus: I think you'd better drop this one. It seems somebody is confused between the game and reality. (I won't name names) He might have some sort of autism. :hmm:

I take it you are referring to me? Please let me refer you to the calculations I have made in game. They give good proof that SH3 is faithful to real-life fuel usage.

http://www.subsim.com/radioroom/show...8&postcount=18

Originally Posted by Corsair

OK here we are again...

Without making tests, it's easy to make a fast calculation.

Let's say a VIIb has an autonomy of 8000 miles at 8 knts (it's close and makes it easier).
We run it on the surface at 8 knts, this gives us 1000 hours (which is the unit used on boats for fuel consumption)
Assuming the weather stays nice and beautiful (for making things easier) our sub A will run 8000 miles @ 8 knots in 41.66 days (1000 hrs / 24)

The same sub B runs in the same nice weather conditions, but is submerged 12 hours @ 3 knts, reloads batteries 3 hrs @ 5 knts and runs surfaced 9 hrs @ 8 Knts every day. This gives us 36 + 15 + 72 = 123 miles a day, which is average 5.125 Knts.

Since our sub B uses its diesels only 12 hrs a day, the 1000 hrs of autonomy give us now 83.33 days, for a total distance of 123 * 83.33 = 10 250 miles

So although it will take twice the time, sub B will travel 2.250 miles i.e. roughly 28% further than sub A in the same weather conditions.

On the bit I have underlined:
You are assuming that because the speed setting is the same; you are using the same amount of fuel. Sub B only uses it's diesels 12 hours a day, but one of the diesels is running at 500rpm for 3 hours in order to charge the batteries. Because one of the motors is running faster the 1000hrs of autonomy no longer applies.

[Corsair]

Oh my God ....

No comment. I let you do the math yourself.
Assuming a differential fuel burning per engine is modelled and the reload engine burns 2 x fuel you will find there is still 1000 extra nautical miles...

Now I am out of the thread

[Sailor Steve]

Corsair, I see two problems:

1) Why isn't sub B recharging his batteries for 3 hours and then diving again? This would seem more practical if you are correct.

2) Asking the same question for the third time, if this works in real life then why aren't surface ships equipped with a similar system to increase their range?

The problem is that the energy available is finite, no matter what the source, and evergy is lost during a transfer process such as recharging batteries. If it worked in real life then real life submariners would have talked about it, and I don't recall reading about anybody claiming to extend patrol distance by this method.

It's a game thing, and if it works in the game then I think the game is wrong.

[Letum]

Originally Posted by Sailor Steve

Corsair, I see two problems:

1) Why isn't sub B recharging his batteries for 3 hours and then diving again? This would seem more practical if you are correct.

2) Asking the same question for the third time, if this works in real life then why aren't surface ships equipped with a similar system to increase their range?

The problem is that the energy available is finite, no matter what the source, and evergy is lost during a transfer process such as recharging batteries. If it worked in real life then real life submariners would have talked about it, and I don't recall reading about anybody claiming to extend patrol distance by this method.

It's a game thing, and if it works in the game then I think the game is wrong.

And according to the mesurements I have done in game, it doesn't work in game so the games not wrong.

[Sinking Fast]

First I'm a newbie and running shiii stock. I'd like to finish my campaign without all the mods. I'm stuck with a IXB with all the goodies because I didn't realize I lose all the goodies when I change boats. Being renown poor (due to every possible upgrade to what appears to be the wrong boat) I don't have the 6500 required to get a IXC anyway.

I've been assigned several endurance runs some of which I didn't appear to have the range to make so I did not try. I've made two endurance runs the first off Halifax and the second off Northfolk. In both cases after I got there and and asking the navigator my maxium range at the current speed he tells me I'm 2000km short of making it home and this at 8 to 9 knots. In one case I still had over half my fuel left according to the gage. In both cases I had increased speed to catch a target and send it to the bottom. In both cases I had let the gage return to normal speed of 8 or 9 knots before asking. In both cases I made it back home with 2000km of fuel to spare running on the surface. I only dive when absolutely neccessary. So far the extra flak gun helps. You tend to drive off single air attacks but it's an expensive upgrade.

The only thing I can think of is there is a bug. The navigator doesn't appear to know you have reduced speed right away even through gage says you have. I guess the Caribbean is out of the question I can't catch tankers moving away at 8 to 9 knots.

Sinking Fast

[Letum]

The navigator's range guess is usually a long way off from your real range.
If you ask him the range twice in rapid succession he will give you two different ranges, often several thousand miles out. He is more accurate in clear weather, but he always gives you a number well under your real range.
This is because he works on your actual speed and not your set/predicted speed.

The best way to calculate range is to guess on your first patrol, but on the way back, wait until the game reports that you have 25% fuel. Once that happens make a mark on the map and set your speed to what ever the most economical speed for your boat is. Now measure the distance you can cover until the game reports 10% fuel. Now times the result by 1.6666666... and you will have your real range.

If you run the same test, but using the submerged running theory you will notice your range has been reduced.

[Dantenoc]

I don't care if you can create energy out of nothing, I'm with Homer:



"In this house we obey the laws of thermodynamics!" :rotfl:

[Ducimus]

Originally Posted by Dantenoc

I don't care if you can create energy out of nothing, I'm with Homer:



"In this house we obey the laws of thermodynamics!" :rotfl:

- tis a shame thermal dynamics dont exist in this game.

[Zero Niner]

Hey Ducimus
Mind if I use your thread necromancy image? There's another forum I post at that could use this...

[Ducimus]

Originally Posted by Zero Niner

Hey Ducimus
Mind if I use your thread necromancy image? There's another forum I post at that could use this...

LOL its not mine, i just google image searched it and used one that allowed remote linking :rotfl:

[Rykaird]

Originally Posted by Ducimus

Yup, one engine is taken "off the line" as the saying goes and put into charging the batteries. Runs at about 500 RPMs (flank speed) for however long it takes to recharge the batteries. Next time your recharging your battries, look at the RPM gauges in the control room.

Yikes! Does this elevate my sound signature and increase chances for being detected?